Method for optimizing passive sensor network protocol

ABSTRACT

Disclosed is a control method for controlling data return and energy optimization in a passive sensor network. The passive sensor network comprises an aggregation node and sensor nodes. The control method comprises an energy calculating step, an energy broadcasting step, an energy collecting step, a clustering step and a data transmitting step. By means of the control method in the embodiments of the present disclosure, data return and energy optimization in a passive sensor network are controlled, so that insofar as all sensor nodes can return data to an aggregation node, the aggregation node consumes the least amount of energy, thereby achieving the optimal energy usage efficiency. Also disclosed is a control device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/096936, filed on Aug. 26, 2016, which takes priority fromChinese Patent Application No. 201610700191.1, filed on Aug. 22, 2016,the contents of each of which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a wireless sensor network technology,and more particularly, to a control method and a control device.

BACKGROUND

The demands for wireless sensor networks will become more and moreextensive with the development of informatization. However, sensor nodesin wireless sensor networks are generally miniaturized devices poweredby batteries, their limited power limits their application in somespecial fields, such as some places that are difficult for human toreach, including ocean, desert and even nuclear radiation areas.Therefore, a new passive wireless sensor network becomes imminent.

Some researches have been carried out on such type of passive sensornetwork at home and abroad; for example, a method mainly used at abroadis to receive and modulate the energy broadcast by an aggregation nodeand then reflect the energy to the aggregation node through the ambientbackscatter of the sensor node. While a method mainly used in china isto collect the weak energy emitted by the sensor node in theenvironment, and to transmit the information to the sink after theenergy is accumulated to a sufficient amount. However, both methods havefatal defects. The first method simply modulates the incident wave andthen reflects it back, which lacks sufficient routing structure andcoding mode, and in order to achieve a satisfactory result, a high powerrequirement for a RF source will be needed. The second method needs anamount of time to enable the sensor node to accumulate enough energy,the method needs to collect the energy in the environment, and if theenergy in the environment changes, the sensor node will be unstable.

SUMMARY

The present disclosure is intended to solve at least one of existingtechnical problems in the prior art. For this purpose, the presentdisclosure needs to provide a control method and a control device.

The control method in the embodiment of the present disclosure is usedfor controlling data return and energy optimization in a passive sensornetwork, the passive sensor network includes an aggregation node andsensor nodes, and the control method includes the following steps:

an energy calculating step of determining an optimum value of energyconsumed by the aggregation node according to a first optimizationtarget and a first constraint condition set;

wherein the first optimization target comprises: minimizing the energyconsumed by the aggregation node in the case that the first constraintcondition set is satisfied; and

the first constraint condition set involves in that: energy received bythe sensor node minus energy consumed by the sensor node to process thedata is greater than energy required by the sensor node to transmit thedata to next sensor node;

an energy broadcasting step of controlling the aggregation node tobroadcast energy to the entire passive sensor network;

an energy collecting step of controlling the sensor nodes to collect theenergy broadcast by the aggregation node;

a clustering step of clustering the sensor nodes and selecting clusterheads according to a predetermined clustering rule; and

a data transmitting step of controlling each of the sensor nodes of eachcluster to transmit data to a corresponding cluster head and then to theaggregation node or one of the sensor nodes of a cluster closer to theaggregation node so as to eventually transmit the data to theaggregation node, and closing the sensor node that completes datatransmission.

In some embodiments, the data comprises at least one of the datacollected by the sensor node itself and the data transmitted by othersensor nodes.

In some embodiments, the data transmitting step specifically includes:

judging whether a current energy of each of the sensor nodes is greaterthan or equal to an energy required for dormancy after the data istransmitted by each of the sensor nodes;

controlling the sensor node to enter a dormant mode when the currentenergy is greater than or equal to the energy required for dormancy; and

controlling to temporarily turn off the sensor node when the currentenergy is less than the energy required for dormancy.

In some embodiments, the data transmitting step specifically includes:

comparing a distance between the corresponding cluster head and theaggregation node with a distance between any of other sensor nodes andthe aggregation node so as to determine the one of the sensor nodes of acluster closer to the aggregation node.

In some embodiments, the data transmitting step specifically includes:

judging whether the one of the sensor nodes of a cluster closer to theaggregation node is the cluster head; and

when the one of the sensor nodes of a cluster closer to the aggregationnode is not the cluster head, transmitting the data to the cluster headpreferably so as to finally transmit the data to the aggregation node.

In some embodiments, the data transmitting step specifically includes:

judging whether the one of the sensor nodes of a cluster closer to theaggregation node survives;

when the one of the sensor nodes of a cluster closer to the aggregationnode survives, judging whether a distance between the one of the sensornodes of a cluster closer to the aggregation node and the aggregationnode is less than a predetermined distance; and

when the distance between the sensor nodes of a cluster closer to theaggregation node and the aggregation node is less than the predetermineddistance, controlling the sensor nodes of a cluster closer to theaggregation node to transmit the data to the aggregation node.

The control device in the embodiment of the present disclosure is usedfor controlling data return and energy optimization in a passive sensornetwork, the passive sensor network includes an aggregation node andsensor nodes, and the control device includes:

an energy calculating module configured to determine an optimum value ofenergy consumed by the aggregation node according to a firstoptimization target and a first constraint condition set;

wherein the first optimization target comprises: minimizing the energyconsumed by the aggregation node in the case that the first constraintcondition set is satisfied; and

the first constraint condition set involves in that: energy received bythe sensor node minus energy consumed by the sensor node to process thedata is greater than energy required by the sensor node to transmit thedata to the next sensor node;

an energy broadcasting module configured to control the aggregation nodeto broadcast energy to the entire passive sensor network;

an energy collecting module configured to control the sensor node tocollect the energy broadcast by the aggregation node;

a clustering module configured to cluster the sensor nodes and selectcluster heads according to a predetermined clustering rule; and

a data transmitting module configured to control each of the sensornodes of each cluster to transmit data to a corresponding cluster headand then to the aggregation node or one of the sensor nodes of a clustercloser to the aggregation node so as to eventually transmit the data tothe aggregation node, and close the sensor node that completes datatransmission.

In some embodiments, the data comprises at least one of the datacollected by the sensor node itself and the data transmitted by othersensor nodes.

In some embodiments, the data transmitting module includes:

a first judging module configured to judge whether a current energy ofeach of the sensor nodes is greater than or equal to an energy requiredfor dormancy after the data is transmitted by each of the sensor nodes;

a first control module configured to control the sensor node to enter adormant mode when the current energy is greater than or equal to theenergy required for dormancy; and

a second control module configured to control to temporarily turn offthe sensor node when the current energy is less than the energy requiredfor dormancy.

In some embodiments, the data transmitting module includes:

a comparing module configured to compare a distance between thecorresponding cluster head and the aggregation node with a distancebetween any of other sensor nodes and the aggregation node so as todetermine the one of the sensor nodes of a cluster closer to theaggregation node.

In some embodiments, the data transmitting module includes:

a second judging module configured to judge whether the one of thesensor nodes of a cluster closer to the aggregation node is the clusterhead; and

the data transmitting module is configured to, when the one of thesensor nodes of a cluster closer to the aggregation node is not thecluster head, transmit the data to the cluster head preferably so as tofinally transmit the data to the aggregation node.

In some embodiments, the data transmitting module includes:

a third judging module configured to judge whether the one of the sensornodes of a cluster closer to the aggregation node survives;

a fourth judging module configured to, when the one of the sensor nodesof a cluster closer to the aggregation node survives, judge whether adistance between the one of the sensor nodes of a cluster closer to theaggregation node and the aggregation node is less than a predetermineddistance; and

the data transmitting module is configured to, when the distance betweenthe one of the sensor nodes of a cluster closer to the aggregation nodeand the aggregation node is less than the predetermined distance,control the one of the sensor nodes of a cluster closer to theaggregation node to transmit the data to the aggregation node.

The control method and the control device in the embodiment of thepresent disclosure minimize the energy consumed by the aggregation nodeon the premise that all the sensor nodes can return the data to theaggregation node through controlling data return and energy optimizationin the passive sensor network, thereby realizing optimum energyutilization efficiency.

The additional aspects and advantages of the present disclosure will bepartially given in the following description, some will become apparentfrom the following description, or will be understood through thepractice of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The description above and/or the additional aspects and advantages ofthe present disclosure will become apparent and easily understood fromthe description to the embodiments with reference to the followingdrawings, wherein:

FIG. 1 is a flow chart of a control method according to an embodiment ofthe present disclosure.

FIG. 2 is a diagram of functional modules of a control device accordingto an embodiment of the present disclosure.

FIG. 3 is another flow chart of the control method according to anembodiment of the present disclosure.

FIG. 4 is still another flow chart of the control method according to anembodiment of the present disclosure.

FIG. 5 is yet another flow chart of the control method according to anembodiment of the present disclosure.

FIG. 6 is a diagram of a wireless sensor network according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examplesof which are illustrated in the accompanying drawings, in which the sameor similar reference numbers throughout the drawings represent the sameor similar elements or elements having same or similar functions.

Embodiments described below with reference to drawings are merelyexemplary and used for explaining the present disclosure, and should notbe understood as limitation to the present disclosure.

Referring to FIG. 1, a control method according to an embodiment of thepresent disclosure is used for controlling data return and energyoptimization in a passive sensor network. The passive sensor networkincludes an aggregation node and sensor nodes. The control methodincludes the following steps:

an energy calculating step S50 of determining an optimum value of energyconsumed by the aggregation node according to a first optimizationtarget and a first constraint condition set;

wherein the first optimization target includes: minimizing the energyconsumed by the aggregation node in the case that the first constraintcondition set is satisfied; and

the first constraint condition set involves in that: energy received bythe sensor node minus energy consumed by the sensor node to process thedata is greater than energy required by the sensor node to transmit thedata to the next sensor node;

an energy broadcasting step S10 of controlling the aggregation node tobroadcast energy to the entire passive sensor network;

an energy collecting step S20 of controlling the sensor nodes to collectthe energy broadcast by the aggregation node;

a clustering step S30 of clustering the sensor nodes and selectingcluster heads according to a predetermined clustering rule; and

a data transmitting step S40 of controlling each of the sensor nodes ofeach cluster to transmit data to the corresponding cluster head and thento the aggregation node or one of the sensor nodes of a cluster closerto the aggregation node so as to eventually transmit the data to theaggregation node, and closing the sensor node that completes datatransmission.

Referring to FIG. 2, a control device 10 according to an embodiment ofthe present disclosure includes an energy calculating module 15, anenergy broadcasting module 11, an energy collecting module 12, aclustering module 13 and a data transmitting module 14.

The control method in the embodiment of the present disclosure can berealized by the control device 10 in the embodiment of the presentdisclosure, for example, the energy calculating step S50 can be realizedby the energy calculating module 15, the energy broadcasting step S10can be realized by the energy broadcasting module 11, the energycollecting step S20 can be realized by the energy collecting module 12,the clustering step S30 can be realized by the clustering module 13, andthe data transmitting step S40 can be realized by the data transmittingmodule 14.

In other words, the energy calculating module 15 can determine anoptimum value of energy consumed by the aggregation node according to afirst optimization target and a first constraint condition set. Theenergy broadcasting module 11 can be configured to control theaggregation node to broadcast energy to the entire passive sensornetwork. The energy collecting module 12 can be configured to controlthe sensor node to collect the energy broadcast by the aggregation node.The clustering module 13 can be configured to cluster the sensor nodesand select cluster heads according to a predetermined clustering rule.The data transmitting module 14 can be configured to control each of thesensor nodes of each cluster to transmit data to the correspondingcluster head and then to the aggregation node or one of the sensor nodesof a cluster closer to the aggregation node so as to eventually transmitthe data to the aggregation node, and close the sensor node thatcompletes data transmission.

The control method and the control device 10 in the embodiment of thepresent disclosure minimize the energy consumed by the aggregation nodeon the premise that all the sensor nodes can return the data to theaggregation node through controlling data return and energy optimizationin the passive sensor network, thereby realizing optimum energyutilization efficiency.

Specifically, assuming that a time of duration for the aggregation nodeto broadcast energy is t, when the energy is freely broadcast in aspace, the energy received by each of the sensor nodes is

$E_{i} = {{P_{t}\left\lbrack \frac{\sqrt{G_{l}}\lambda}{4\pi \; d_{i}} \right\rbrack}^{2}t}$

where P_(t) is transmitting power, √{square root over (G₁)} is antennagain, λ is wavelength, and d_(i) is distance between the sensor node andan access point.

Further, each of the sensor nodes includes a transmitting end and areceiving end, which can be used to process data received andtransmitted by the sensor node. Assuming that E_(tx) is energy consumedby the transmitting end to process one bit, E_(rx) is energy consumed bythe receiving end to process one bit, E_(mp) is energy consumed by thesensor node to transmit one bit for a unit distance, k_(i) is a numberof bits received by the cluster head in the i^(th) round, k₀ is a numberof bits averagely transmitted by each of the sensor nodes, p is aprobability that the sensor nodes become the cluster head in each round,and f(d_(i),d_(i+1)) is an average value of a minimum distance betweenthe cluster head in the i^(th) round and the cluster head in thei+1^(th) round, we can obtain:

f(d _(i) ,d _(i+1))²=θ²(d _(i) −d _(i+1))²

where θ>1, and θ can be determined according to actual condition. Themore intensive the sensor nodes are distributed, the smaller the θ is;and the sparser the sensor nodes are distributed, the larger the θ is.We can obtain:

$k_{i} = \frac{k_{0}d_{0}^{2}}{{pd}_{i}^{2}}$$E_{i} = \frac{C}{d_{i}^{2}}$

The first optimization target includes: minimizing the energy consumedby the aggregation node in the case that the first constraint conditionset is satisfied; and

the first constraint condition set involves in that: energy received bythe sensor node minus energy consumed by the sensor node to process thedata is greater than energy required by the sensor node to transmit thedata to the next sensor node.

In this way, on the premise that the data of all sensor nodes can bereturned to the aggregation node, the energy consumed by the aggregationnode is optimized, thereby realizing the optimum energy utilizationefficiency.

We can define the energy utilization efficiency as

${\eta = \frac{K}{C}},{C = \frac{P_{t}{tG}_{l}\lambda^{2}}{16\pi^{2}}},$

where k is an integrated number of data bits received by the accesspoint.

On the premise that a data volume K of the sensor node is constant, theoptimum energy utilization efficiency means optimum transmission energy.The problem to be solved lies in: minimizing energy C consumed by theaggregation node on the premise that energy received by the sensor nodeminus energy consumed by the sensor node to process the data is greaterthan energy required by the sensor node to transmit the data to the nextsensor node, i.e.:

$s.t.\mspace{14mu} \begin{matrix}{\min \mspace{14mu} C} \\{{\frac{C}{d_{0}^{2}} - {E_{tx}*k_{0}}} > {E_{mp}*k_{0}*{f\left( {d_{0},d_{1}} \right)}^{2}}}\end{matrix}$

In order to make sure that each of the sensor nodes can successfullycomplete data return, and so on in a similar fashion,

${\frac{C}{d_{i}^{2}} - {E_{tx}*k_{i}} - {E_{rx}*k_{i}}} > {E_{mp}*k_{i}*{f\left( {d_{i},d_{i + 1}} \right)}^{2}}$

we can obtain:

f(c)>θd ₀

Thus, an optimum value C_(min) of the energy C consumed by theaggregation node is solved, the aggregation node broadcasts the energyto the entire passive sensor network according to the optimum valueC_(min), and the sensor nodes further complete the subsequent energyreceiving and information collecting tasks.

It is to be understood that the sensor nodes in the embodiments of thepresent disclosure include the cluster heads.

In some embodiments, the data comprises at least one of the datacollected by the sensor node itself and the data transmitted by othersensor nodes. For example, the sensor node only transmit the datacollected by itself when the sensor node is the outermost sensor node,and the sensor node transmit both the data collected by the sensor nodeand the data transmitted by other sensor nodes when the number of datatransmission is two or more. In this way, the data can be transmittedlayer by layer, so that the useful data can be completely transmitted tothe aggregation node.

Referring to FIG. 3, in some embodiments, the data transmitting step S40specifically includes:

step S41 of judging whether a current energy of each of the sensor nodesis greater than or equal to an energy required for dormancy after thedata is transmitted by each of the sensor nodes;

step S42 of controlling the sensor node to enter a dormant mode when thecurrent energy is greater than or equal to the energy required fordormancy; and

step S43 of controlling to temporarily turn off the sensor node when thecurrent energy is less than the energy required for dormancy.

In some embodiments, the data transmitting module 14 includes a firstjudging module 141, a first control module 142 and a second controlmodule 143. The step S41 can be realized by the first judging module141, the step S42 can be realized by the first control module 142, andthe step S43 can be realized by the second control module 143.

In other words, the first judging module 141 can be configured to judgewhether a current energy of each of the sensor nodes is greater than orequal to an energy required for dormancy after the data is transmittedby each of the sensor nodes. The first control module 142 can beconfigured to control the sensor node to enter a dormant mode when thecurrent energy is greater than or equal to the energy required fordormancy. The second control module 143 can be configured to control totemporarily turn off the sensor node when the current energy is lessthan the energy required for dormancy.

In this way, the energy consumption can be reduced through controllingthe sensor node completing data transmission to enter a dormant mode ortemporarily turning off the sensor node, and after a new round of energybroadcasting process is started, the sensor node temporarily turned offcan collect energy and start to operate again.

Referring to FIG. 4, in some embodiments, the data transmitting step S40specifically includes:

step S44 of comparing a distance between the corresponding cluster headand the aggregation node with a distance between any of other sensornodes and the aggregation node so as to determine the one of the sensornodes of a cluster closer to the aggregation node.

In some embodiments, the data transmitting module 14 includes acomparing module 144. The step S44 can be realized by the comparingmodule 144.

In other words, the comparing module 144 can be configured to compare adistance between the corresponding cluster head and the aggregation nodewith a distance between any of other sensor nodes and the aggregationnode so as to determine the one of the sensor nodes of a cluster closerto the aggregation node.

In this way, the data can be transmitted to the aggregation node fromfar to near. The sensor nodes closer to the aggregation node can havemore energy, after determining the sensor nodes closer to theaggregation node, transmission of the data to the sensor nodes closer tothe aggregation node can enable the sensor nodes to have sufficientenergy to finally transmit the data to the aggregation node.

Referring to FIG. 5, in some embodiments, the data transmitting step S40specifically includes:

step S45 of judging whether the one of the sensor nodes of a clustercloser to the aggregation node is the cluster head; and

step S46 of, when the one of the sensor nodes of a cluster closer to theaggregation node is not the cluster head, transmitting the data to thecluster head preferably so as to finally transmit the data to theaggregation node.

In some embodiments, the data transmitting module 14 includes a secondjudging module 145. The step S45 can be realized by the second judgingmodule 145, and the step S46 can be realized by the data transmittingmodule 14.

In other words, the second judging module 145 can be configured to judgewhether the one of the sensor nodes of a cluster closer to theaggregation node is the cluster head. The data transmitting module 14can be configured to, when the one of the sensor nodes of a clustercloser to the aggregation node is not the cluster head, transmit thedata to the cluster head preferably so as to finally transmit the datato the aggregation node.

The control method in the embodiments of the present disclosure does notnecessarily require the sensor nodes or the cluster heads to transmitdata to the next cluster head, when the energy of the sensor nodes orthe cluster heads is small, the data only needs to be transmitted to thesensor nodes closer to the aggregation node as far as possible, and thenthe sensor nodes closer to the aggregation node preferably transmit thedata to the cluster heads of the sensor nodes. Preferred transmission tothe cluster heads of the sensor nodes is corresponding to the foregoingpredetermined clustering rule, and in terms of relative position andcurrent energy, the cluster heads are bound to have more advantages thanthe sensor nodes, and can transmit data more effectively.

In some embodiments, the data transmitting step S40 specificallyincludes:

step S47 of judging whether the one of the sensor nodes of a clustercloser to the aggregation node survives;

step S48 of, when the one of the sensor nodes of a cluster closer to theaggregation node survives, judging whether a distance between the one ofthe sensor nodes of a cluster closer to the aggregation node and theaggregation node is less than a predetermined distance; and

step S49 of, when the distance between the one of the sensor nodes of acluster closer to the aggregation node and the aggregation node is lessthan the predetermined distance, controlling the one of the sensor nodesof a cluster closer to the aggregation node to transmit the data to theaggregation node.

In some embodiments, the data transmitting module 14 includes a thirdjudging module 146 and a fourth judging module 147. The step S47 can berealized by the third judging module 146, the step S48 can be realizedby the fourth judging module 147, and the step S49 can be realized bythe data transmitting module 14.

In other words, the third judging module 146 can be configured to judgewhether the one of the sensor nodes of a cluster closer to theaggregation node survives. The fourth judging module 147 can beconfigured to, when the one of the sensor nodes of a cluster closer tothe aggregation node survives, judge whether a distance between the oneof the sensor nodes of a cluster closer to the aggregation node and theaggregation node is less than a predetermined distance. The datatransmitting module 14 can be configured to, when the distance betweenthe one of the sensor nodes of a cluster closer to the aggregation nodeand the aggregation node is less than the predetermined distance,control the one of the sensor nodes of a cluster closer to theaggregation node to transmit the data to the aggregation node.

When the distance between the survived sensor node and the aggregationnode is less than the predetermined distance, the data can betransmitted to the aggregation node through the sensor nodes. More thanone survived sensor nodes with the distance from the aggregation nodeless than the predetermined distance are arranged. In this way, thesesensor nodes can be prevented from transmitting the data to one sensornode closest to the aggregation node, which results in increasedtransmission times and unnecessary energy consumption.

The control method in the embodiment of the present disclosure isdescribed in detail below by way of example. Referring to FIG. 6, in awireless sensor network, a sensor node set is {S}={S₁, . . . , S_(n)},where n is a number of sensors in the network. An identification of theaggregation node is AP. The aggregation node AP broadcasts energy to thewhole network, and all sensor nodes collect the energy broadcast by theaggregation node AP. In the control method of the embodiment, the energyfor the sensor nodes to receive signal, process data and return datacomes from the energy broadcast by the aggregation node AP, the sensornodes far away from the aggregation node AP have relatively poor dataprocessing ability, the nodes close to the aggregation node AP collectmuch energy, and have more data processing tasks.

According to the clustering rule f(E₁, . . . , E_(n), d₁, . . . ,d_(n)), several outermost clusters are formed, and the cluster heads areidentified as {C_(a,b,c)}, where a is a number of layers of the clusterscurrently formed, b is a serial number of the cluster, and c is thetransmission times. The number of nodes in each cluster is not alwaysthe same. The sensor nodes in the cluster transmit the data to thecluster heads to save energy and enter dormancy or are temporarilyturned off if the energy is insufficient.

Some nodes at the outermost layer such as S₁ transmit the data to thecluster head C_(1,m,1) of the nodes, where 1 represents the first layer,m represents a sequence number of the cluster in the second layer, and 1represents the first transmission. The sensor node of C_(1,m,1) in thenetwork is marked as S_(r1), where r1 is a specific serial number.

C_(1,m,1)(S_(r1)) transmits the information of the cluster according tothe energy of the nodes closer to AP. For example, the data istransmitted to one node S_(r2) that is closer to AP. S_(r2) is notnecessarily the cluster head. In the passive sensor network, the sensornode has a higher probability of returning the data to the cluster headof the sensor node, but the data is not 100% transmitted to the clusterhead, and a considerable probability that the data can be transmitted tosome node in the adjacent cluster or the high-level cluster exists. WhenS_(r2) is the cluster head, S_(r2)(C_(2,n,2)) continues to transmit thedata to one node S_(r1) closer to AP. When S_(r2) is not the clusterhead, S_(r2) transmits the data to the cluster head C_(2,n,3) of thecluster where S_(r2) is located, where 2 represents the second layer ofcluster, n represents a serial number of the cluster at the secondlayer, and 3 represents the third transmission. If the energy saved bythe cluster head C_(2,n,3) where S_(r2) is located has lower ability toprocess data, S_(r2) can bypass the cluster head where S_(r2) is locatedand select some node in the adjacent cluster or the high-layer clusterfor transmission.

For example, as shown in the drawing, a data transmitting route isS₁→C_(1,1,1)(S_(r1))→C_(2,1,2)(S_(r2))→S_(r3) (some sensornode)→C_(3,1,4)(S_(r4))(where r1, r2, r3 and r4 are some specific serialnumbers).

By analogy, the last data can be transmitted to the nodeC_(a′,b′,c′)(S_(r′)) within a certain range from the aggregation node,and the node C_(a′,b′,c′)(S_(r′)) returns the data to AP. Each nodeforms own route {C_(1,*,*)(S_(r)), C_(2,*,*)(S_(r)) . . . }, where * isa serial number, which can change according to the condition of eachround of the network.

In this way, each node forms a set of data return routes, the datareturn routes of the nodes close to the aggregation node AP are includedin the routes of the nodes far away from the aggregation node AP.

After the data is returned to the aggregation node AP, this round isended. The next round is conducted, the aggregation node AP broadcastsenergy again, and the nodes return the data according to the rule above.Each round of the data return route is continuously changed. In thisway, each of the sensor nodes in the network transmits useful data tothe aggregation node with maximum probability during each round of datareturn.

In the description of the embodiments of the present disclosure, it isto be understood that the orientation or position relationship indicatedby the terms such as “center”, “longitudinal”, “lateral”, “length”,“width”, “thickness”, “up”, “down”, “front”, “rear”, “left”, “right”,“vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”,“clockwise”, and “counterclockwise” is the orientation or positionrelationship based on the drawings, which are merely for the convenienceof description to the embodiments of the present invention and thesimplification of description, and do not indicate or imply that thedevice or element referred to must have or operated in a particularorientation. They cannot be seen as limits to the present disclosure.Moreover, terms of “first” and “second” are only used for descriptionand cannot be seen as indicating or implying relative importance orindicating or implying the number of the indicated technical features.Thus, the features defined with “first” and “second” may comprise orimply at least one of these features. In the description of the presentdisclosure, “a plurality of” means two or more than two, unlessspecified otherwise.

In the present disclosure, unless specified or limited otherwise, theterms “mounted,” “connected,” “coupled,” “fixed” and the like are usedbroadly, and may be, for example, fixed connections, detachableconnections, or integral connections; may also be mechanical orelectrical connections; may also be direct connections or indirectconnections via intervening structures; may also be inner communicationsof two elements or interactions of two elements, which can be understoodby those skilled in the art according to specific situations.

In the present disclosure, unless specified or limited otherwise, astructure in which a first feature is “on” a second feature may includean embodiment in which the first feature directly contacts the secondfeature, and may also include an embodiment in which the first featureindirectly contacts the second feature via an intermediate medium.Moreover, a structure in which a first feature is “on”, “over” or“above” a second feature may indicate that the first feature is rightabove the second feature or obliquely above the second feature, or justindicate that a horizontal level of the first feature is higher than thesecond feature. A structure in which a first feature is “below”, or“under” a second feature may indicate that the first feature is rightunder the second feature or obliquely under the second feature, or justindicate that a horizontal level of the first feature is lower than thesecond feature.

Various embodiments and examples are provided in the followingdescription to implement different structures of the present disclosure.In order to simplify the present disclosure, certain elements andsettings will be described. However, these elements and settings areonly examples and are not intended to limit the present disclosure. Inaddition, reference numerals may be repeated in different examples inthe disclosure. This repeating is for the purpose of simplification andclarity and does not refer to relations between different embodimentsand/or settings. Furthermore, examples of different processes andmaterials are provided in the present disclosure. However, it would beappreciated by those skilled in the art that other processes and/ormaterials may be also applied.

Reference throughout this specification to “an embodiment”, “someembodiments”, “exemplary embodiment”, “an example”, “a specificexample”, or “some examples” means that a particular feature, structure,material, or characteristic described in connection with the embodimentor example is included in at least one embodiment or example of thepresent disclosure. In this specification, exemplary descriptions ofaforesaid terms are not necessarily referring to the same embodiment orexample. Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments or examples.

Any process or method described in a flow chart or described herein inother ways may be understood to include one or more modules, segments orportions of codes of executable instructions for achieving specificlogical functions or steps in the process, and the scope of a preferredembodiment of the present disclosure includes other implementations,wherein the order of execution may differ from that which is depicted ordiscussed, including according to involved function, executingconcurrently or with partial concurrence or in the contrary order toperform the function, which should be understood by those skilled in theart.

The logic and/or step described in other manners herein or shown in theflow chart, for example, a particular sequence table of executableinstructions for realizing the logical function, may be specificallyachieved in any computer readable medium to be used by the instructionexecution system, device or equipment (such as the system based oncomputers, the system comprising processors or other systems capable ofacquiring the instruction from the instruction execution system, deviceand equipment and executing the instruction), or to be used incombination with the instruction execution system, device and equipment.As to the specification, “the computer readable medium” may be anydevice adaptive for including, storing, communicating, propagating ortransferring programs to be used by or in combination with theinstruction execution system, device or equipment. More specificexamples of the computer-readable medium comprise but are not limitedto: an electronic connection (an electronic device) with one or morewires, a portable computer enclosure (a magnetic device), a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or a flash memory), an optical fiber device anda portable compact disk read-only memory (CDROM). In addition, thecomputer-readable medium may even be a paper or other appropriate mediumcapable of printing programs thereon, this is because, for example, thepaper or other appropriate medium may be optically scanned and thenedited, decrypted or processed with other appropriate methods whennecessary to obtain the programs in an electric manner, and then theprograms may be stored in the computer memories.

It should be understood that each part of the present disclosure may berealized by hardware, software, firmware or their combination. In theabove embodiments, a plurality of steps or methods may be realized bythe software or firmware stored in the memory and executed by theappropriate instruction execution system. For example, if it is realizedby the hardware, likewise in another embodiment, the steps or methodsmay be realized by one or a combination of the following techniquesknown in the art: a discrete logic circuit having a logic gate circuitfor realizing a logic function of a data signal, an application-specificintegrated circuit having an appropriate combination logic gate circuit,a programmable gate array (PGA), a field programmable gate array (FPGA),etc.

Those skilled in the art shall understand that all or parts of the stepsin the above exemplifying method for the present disclosure may beachieved by commanding the related hardware with programs, the programsmay be stored in a computer-readable storage medium, and the programscomprise one or a combination of the steps in the method embodiments ofthe present disclosure when running on a computer.

In addition, each function cell of the embodiments of the presentdisclosure may be integrated in a processing module, or these cells maybe separate physical existence, or two or more cells are integrated in aprocessing module. The integrated module may be realized in a form ofhardware or in a form of software function modules. When the integratedmodule is realized in a form of software function module and is sold orused as a standalone product, the integrated module may be stored in acomputer-readable storage medium.

The storage medium mentioned above may be read-only memories, magneticdisks, CD, etc.

Although embodiments of present disclosure have been shown and describedabove, it should be understood that above embodiments are justexplanatory, and cannot be construed to limit the present disclosure,for those skilled in the art, changes, alternatives, and modificationscan be made to the embodiments without departing from scope of thepresent disclosure.

What is claimed is:
 1. A control method for controlling data return andenergy optimization in a passive sensor network, wherein the passivesensor network comprises an aggregation node and sensor nodes, and thecontrol method comprises the following steps: an energy calculating stepof determining an optimum value of energy consumed by the aggregationnode according to a first optimization target and a first constraintcondition set; wherein the first optimization target comprises:minimizing the energy consumed by the aggregation node in the case thatthe first constraint condition set is satisfied; and the firstconstraint condition set involves in that: energy received by the sensornode minus energy consumed by the sensor node to process the data isgreater than energy required by the sensor node to transmit the data tonext sensor node; an energy broadcasting step of controlling theaggregation node to broadcast energy to the entire passive sensornetwork; an energy collecting step of controlling the sensor nodes tocollect the energy broadcast by the aggregation node; a clustering stepof clustering the sensor nodes and selecting cluster heads according toa predetermined clustering rule; and a data transmitting step ofcontrolling each of the sensor nodes of each cluster to transmit data toa corresponding cluster head and then to the aggregation node or one ofthe sensor nodes of a cluster closer to the aggregation node so as toeventually transmit the data to the aggregation node, and closing thesensor node that completes data transmission.
 2. The control methodaccording to claim 1, wherein the data comprises at least one of thedata collected by the sensor node itself and the data transmitted byother sensor nodes.
 3. The control method according to claim 1, whereinthe data transmitting step specifically comprises: judging whether acurrent energy of each of the sensor nodes is greater than or equal toan energy required for dormancy after the data is transmitted by each ofthe sensor nodes; controlling the sensor node to enter a dormant modewhen the current energy is greater than or equal to the energy requiredfor dormancy; and controlling to temporarily turn off the sensor nodewhen the current energy is less than the energy required for dormancy.4. The control method according to claim 1, wherein the datatransmitting step specifically comprises: comparing a distance betweenthe corresponding cluster head and the aggregation node with a distancebetween any of other sensor nodes and the aggregation node so as todetermine the one of the sensor nodes of a cluster closer to theaggregation node.
 5. The control method according to claim 1, whereinthe data transmitting step specifically comprises: judging whether theone of the sensor nodes of a cluster closer to the aggregation node isthe cluster head; and when the one of the sensor nodes of a clustercloser to the aggregation node is not the cluster head, transmitting thedata to the cluster head preferably so as to finally transmit the datato the aggregation node.
 6. The control method according to claim 1,wherein the data transmitting step specifically comprises: judgingwhether the one of the sensor nodes of a cluster closer to theaggregation node survives; when the one of the sensor nodes of a clustercloser to the aggregation node survives, judging whether a distancebetween the one of the sensor nodes of a cluster closer to theaggregation node and the aggregation node is less than a predetermineddistance; and when the distance between the one of the sensor nodes of acluster closer to the aggregation node and the aggregation node is lessthan the predetermined distance, controlling the one of the sensor nodesof a cluster closer to the aggregation node to transmit the data to theaggregation node.
 7. A control device for controlling data return andenergy optimization in a passive sensor network, wherein the passivesensor network comprises an aggregation node and sensor nodes, and thecontrol device comprises: an energy calculating module configured todetermine an optimum value of energy consumed by the aggregation nodeaccording to a first optimization target and a first constraintcondition set; wherein the first optimization target comprises:minimizing the energy consumed by the aggregation node in the case thatthe first constraint condition set is satisfied; and the firstconstraint condition set involves in that: energy received by the sensornode minus energy consumed by the sensor node to process the data isgreater than energy required by the sensor node to transmit the data tothe next sensor node; an energy broadcasting module configured tocontrol the aggregation node to broadcast energy to the entire passivesensor network; an energy collecting module configured to control thesensor node to collect the energy broadcast by the aggregation node; aclustering module configured to cluster the sensor nodes and selectcluster heads according to a predetermined clustering rule; and a datatransmitting module configured to control each of the sensor nodes ofeach cluster to transmit data to a corresponding cluster head and thento the aggregation node or one of the sensor nodes of a cluster closerto the aggregation node so as to eventually transmit the data to theaggregation node, and close the sensor node that completes datatransmission.
 8. The control device according to claim 7, wherein thedata comprises at least one of the data collected by the sensor nodeitself and the data transmitted by other sensor nodes.
 9. The controldevice according to claim 7, wherein the data transmitting modulecomprises: a first judging module configured to judge whether a currentenergy of each of the sensor nodes is greater than or equal to an energyrequired for dormancy after the data is transmitted by each of thesensor nodes; a first control module configured to control the sensornode to enter a dormant mode when the current energy is greater than orequal to the energy required for dormancy; and a second control moduleconfigured to control to temporarily turn off the sensor node when thecurrent energy is less than the energy required for dormancy.
 10. Thecontrol device according to claim 7, wherein the data transmittingmodule comprises: a comparing module configured to compare a distancebetween the corresponding cluster head and the aggregation node with adistance between any of other sensor nodes and the aggregation node soas to determine the one of the sensor nodes of a cluster closer to theaggregation node.
 11. The control device according to claim 7, whereinthe data transmitting module comprises: a second judging moduleconfigured to judge whether the one of the sensor nodes of a clustercloser to the aggregation node is the cluster head; and the datatransmitting module is configured to, when the one of the sensor nodesof a cluster closer to the aggregation node is not the cluster head,transmit the data to the cluster head preferably so as to finallytransmit the data to the aggregation node.
 12. The control deviceaccording to claim 7, wherein the data transmitting module comprises: athird judging module configured to judge whether the one of the sensornodes of a cluster closer to the aggregation node survives; a fourthjudging module configured to, when the sensor nodes of a cluster closerto the aggregation node survives, judge whether a distance between theone of the sensor nodes of a cluster closer to the aggregation node andthe aggregation node is less than a predetermined distance; and the datatransmitting module is configured to, when the distance between the oneof the sensor nodes of a cluster closer to the aggregation node and theaggregation node is less than the predetermined distance, control theone of the sensor nodes of a cluster closer to the aggregation node totransmit the data to the aggregation node.